A method for recycling ethylene dichlorocarbonate to produce vinylene carbonate

Abstract

The application discloses a method for preparing vinylene carbonate by recycling ethylene dicarbonochloride. The method comprises the following steps: (1) mixing activated carbon@zinc powder, organic solvent and polymerization inhibitor uniformly, then starting stirring and carrying out nitrogen replacement; (2) adding ethylene dicarbonochloride with a concentration of 37wt% dropwise at a certain temperature, and carrying out reaction under insulation; (3) after the reaction is completed, solid-liquid separation and washing are carried out, the washing liquid and the filtrate are combined, and vinylene carbonate is obtained through pressure reduction desolventization. The activated carbon@zinc powder is gaseous zinc element generated after zinc chloride obtained through filtration after the reaction is completed is introduced into activated carbon particles through a series of reactions. The application effectively utilizes ethylene dicarbonochloride, reduces environmental pollution, improves the yield of vinylene carbonate by using activated carbon@zinc powder, realizes cyclic utilization of by-products in the preparation of vinylene carbonate, and reduces production cost.

Description

Technical Field

[0001] This invention belongs to the field of raw materials for lithium-ion battery electrolyte additives, and specifically relates to a method for preparing vinylene carbonate by recycling ethylene dichlorocarbonate. Background Technology

[0002] Ethylene carbonate (VC) is a high-performance electrolyte additive for lithium-ion batteries. It can act as a film-forming additive to protect the electrodes, as well as slow down capacity decay and extend cycle life. Currently, it is widely used in commercial lithium-ion batteries as a mature product.

[0003] The main method for preparing vinylene carbonate in China is the dechlorination reaction of chloroethylene carbonate. Chloroethylene carbonate originates from the substitution reaction between chlorine and ethylene carbonate, with dichloroethylene carbonate (DCEC) as a byproduct. However, DCEC has a high chlorine content, making waste disposal difficult, requiring sophisticated treatment equipment, and incurring high costs.

[0004] To address the current problem of difficult disposal of the byproduct ethylene dichlorocarbonate, a method for resource utilization is needed. This method involves purifying ethylene dichlorocarbonate and enriching the byproduct ethylene dichlorocarbonate to prepare vinylene carbonate. The method should be simple, safe, and easy to separate in the later stages. Furthermore, the expensive dechlorination agent should be regenerated and recycled to effectively reduce production costs. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to design a method for preparing vinylene carbonate by recycling dichloroethylene carbonate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing vinylene carbonate from the recycling of dichloroethylene carbonate includes the following steps: (1) After the activated carbon@zinc powder is mixed evenly with the organic solvent and the polymerization inhibitor, it is added to the reaction vessel and stirred to carry out nitrogen replacement; the organic solvent is one or more of ethyl acetate, methyl tert-butyl ether, and dimethyl carbonate; (2) After heating to 60-80℃, add 37wt% dichloroethylene carbonate to the reaction vessel and keep the reaction at this temperature for 4-8 hours; (3) After the reaction is completed, solid-liquid separation is performed to obtain solid zinc chloride and activated carbon. The zinc chloride and activated carbon are washed, and the washing liquid and filtrate are combined and desolventized under reduced pressure to obtain vinylene carbonate.

[0007] Further, in step (1), the preparation process of activated carbon@zinc powder is as follows: after the zinc chloride solution reacts with 25% ammonia water to generate zinc hydroxide precipitate, it is calcined and reduced by coke to generate gaseous zinc element. The gaseous zinc element is loaded into activated carbon particles through sublimation to obtain activated carbon@zinc powder; further, the mass ratio of activated carbon particles to gaseous zinc element is 1:(2~4).

[0008] Furthermore, the calcination temperature is 200–350°C, and the coke reduction temperature is 1000–1200°C; even further, the calcination temperature is 230°C, and the coke reduction temperature is 1100°C.

[0009] Further, after washing the solid zinc chloride and activated carbon in step (3), they are dried, dissolved in water, filtered to separate the activated carbon and zinc chloride solution. The zinc chloride solution is then precipitated with ammonia, calcined, and reduced with coke to obtain gaseous elemental zinc, which is then condensed and loaded onto activated carbon particles to obtain activated carbon@zinc powder.

[0010] Further, the mass ratio of the 37wt% dichloroethylene carbonate, activated carbon@zinc powder, organic solvent and polymerization inhibitor is (75-175):(60-200):(50-200):(1-2).

[0011] Further, in step (1), the organic solvent is dimethyl carbonate.

[0012] Further, in step (1), the polymerization inhibitor is one or more of 2,6-di-tert-butyl-p-methylphenol and 2,5-tert-di-tert-butylhydroquinone; even further, the polymerization inhibitor is 2,6-di-tert-butyl-p-methylphenol.

[0013] Further, in step (2), the 37wt% dichloroethylene carbonate is prepared by the following method: crude chloroethylene carbonate containing 82wt% chloroethylene carbonate, 7wt% dichloroethylene carbonate, 8wt% ethylene carbonate, water and other impurities is used as raw material, and after separating the chloroethylene carbonate by vacuum distillation, it is dehydrated by molecular sieve.

[0014] Furthermore, the pressure of the vacuum distillation is -0.8 to -0.9 barG, and the temperature is 90 to 130°C; even further, the pressure of the vacuum distillation is -0.9 barG, and the temperature is 97°C.

[0015] Further, in step (3), the amount of detergent used for washing is 15-40g; even further, the amount of detergent used for washing is 30g.

[0016] Further, the detergent is one or more of ethyl acetate, methyl tert-butyl ether, and dimethyl carbonate; even further, the detergent is dimethyl carbonate.

[0017] Compared with the prior art, the positive and beneficial effects achieved by the present invention are as follows: 1. This invention uses activated carbon particles loaded with zinc powder as a dechlorinating agent to control the reaction rate within a suitable range, so that it will not cause the internal mixture temperature to rise due to the excessively fast reaction rate of zinc powder, which is prone to polymerization side reactions; nor will it cause the overall reaction to be very slow due to the small contact area of ​​zinc particles.

[0018] 2. The zinc chloride recycling technology used in this invention not only enables the dechlorination agent to be regenerated and recycled, but also effectively reduces production costs.

[0019] 3. The method for preparing vinylene carbonate of the present invention enables the effective utilization of dichloroethylene carbonate, a byproduct of the vinylene chloride carbonate produced by our company. This not only reduces the difficulty of waste disposal but also yields a high-value-added product, reduces environmental pollution, and effectively saves environmental protection costs. Attached Figure Description

[0020] Figure 1 This is an experimental flowchart of the preparation method of the present invention. Detailed Implementation

[0021] The present invention will be further illustrated below with specific embodiments. These embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] Vinyl dichlorocarbonate with a raw material concentration of 37 wt% was prepared by the following method: Crude vinyl chloride carbonate containing 82 wt% vinyl chloride carbonate (CEC), 7 wt% vinyl dichlorocarbonate (DCEC), 8 wt% vinyl carbonate (EC), 100 ppm water, and other impurities was added to a three-necked flask. The flask was evacuated to -0.9 barG using a vacuum pump, and the mixture was stirred and heated to 97°C. The distillate was collected using a condenser, yielding a distillate containing 36.8 wt% DCEC and other impurities (EC, CEC, and water). The remaining three-necked flask contained 90.10 wt% CEC. The distillate was then dehydrated by adsorption using an adsorption column packed with 3A molecular sieves to obtain DCEC with a concentration of 37.0 wt%. Example 1

[0023] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) After adding 25% ammonia water to zinc chloride solution, zinc hydroxide precipitate is generated. The zinc hydroxide precipitate is filtered and washed with water. The zinc hydroxide precipitate is calcined at 230°C to obtain zinc oxide. The zinc oxide is placed in a blast furnace, coke is added and reduced at 1100°C to obtain gaseous elemental zinc. The gaseous elemental zinc is condensed and loaded into an activated carbon particle reaction vessel in an insulated pipe to obtain activated carbon@zinc powder, wherein the mass ratio of activated carbon to gaseous elemental zinc is 1:3.125. (2) Weigh 82.5g of activated carbon@zinc powder, 140g of dimethyl carbonate and 1.1g of 2,6-di-tert-butyl-p-methylphenol, mix them evenly and add them to the reaction vessel. Start stirring and purge with nitrogen for 30 minutes. (3) Heat to 75°C, keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (4) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. The particles are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 150g of zinc chloride and activated carbon particles. The washing liquid and filtrate are combined and desolventized under reduced pressure to obtain 74.1g of vinylene carbonate with a purity of 98.4% and a yield of 90%. (5) Dissolve zinc chloride and activated carbon granules in 500 mL of water, filter, add 250 g of 25% ammonia water to the filtrate to generate zinc hydroxide precipitate, filter the zinc hydroxide precipitate and wash it with water; calcine the zinc hydroxide precipitate at 230 °C to obtain 205 g of zinc oxide; put the zinc oxide into a blast furnace, add 70 g of coke and reduce it at 1100 °C to obtain gaseous elemental zinc; condense the gaseous elemental zinc in an activated carbon granule reaction vessel in an insulated pipe to obtain activated carbon@zinc powder. Control the loading amount so that the mass ratio of activated carbon to gaseous elemental zinc in the prepared dechlorination agent is 1:3.125. Example 2

[0024] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) The preparation method of activated carbon@zinc powder is basically the same as step (1) in Example 1, except that the mass ratio of activated carbon to gaseous zinc is 1:4. (2) Weigh 82.5g of activated carbon@zinc powder, 140g of dimethyl carbonate and 1.1g of 2,6-di-tert-butyl-p-methylphenol, mix them evenly and add them to the reaction vessel. Start stirring and purge with nitrogen for 30 minutes. (3) Heat to 75°C, keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (4) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 167g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 69.8g of vinylene carbonate with a purity of 97.2% and a yield of 85%. Example 3

[0025] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) The preparation method of activated carbon@zinc powder is the same as step (1) in Example 1; (2) Weigh 82.5g activated carbon@zinc powder, 140g dimethyl carbonate and 1.1g 2,6-di-tert-butyl-p-methylphenol, mix them evenly and add them to the reaction vessel. Start stirring and purge with nitrogen for 30 minutes. (3) Heat to 60°C; keep stirring, weigh 150g of 37wt% DCEC and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (4) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 135g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 60.4g of vinylene carbonate with a purity of 94.4% and a yield of 72%. Example 4

[0026] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) The preparation method of activated carbon@zinc powder is the same as step (1) in Example 1; (2) Weigh 82.5g activated carbon@zinc powder, 140g dimethyl carbonate and 1.1g 2,6-di-tert-butyl-p-methylphenol, mix them evenly and add them to the reaction vessel. Start stirring and purge with nitrogen for 30 minutes. (3) Heat to 80°C; keep stirring, weigh 150g of 37wt% DCEC and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (4) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. The particles are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 150g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 74.0g of vinylene carbonate with a purity of 98.2% and a yield of 90%. Example 5

[0027] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) The preparation method of activated carbon@zinc powder is the same as step (1) in Example 1; (2) Weigh 200g activated carbon@zinc powder, 140g dimethyl carbonate, and 1.1g 2,6-di-tert-butyl-p-methylphenol, mix them evenly, add them to the reaction vessel, start stirring, and purge with nitrogen for 30 minutes. (2) Heat to 75°C, keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (3) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 260g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 73.8g of vinylene carbonate with a purity of 97.9% and a yield of 90%. Example 6

[0028] A method for preparing vinylene carbonate from the recycling of ethylene dichlorocarbonate, the method comprising the following steps: (1) The preparation method of activated carbon@zinc powder is the same as step (1) in Example 1; (2) Weigh 100g activated carbon@zinc powder, 140g dimethyl carbonate, and 1.1g 2,6-di-tert-butyl-p-methylphenol, mix them evenly, add them to the reaction vessel, start stirring, and purge with nitrogen for 30 minutes. (2) Heat to 75°C, keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (3) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 168g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 72.8g of vinylene carbonate with a purity of 97.6% and a yield of 90%.

[0029] Comparative Example 1 The preparation method for vinylene carbonate by replacing activated carbon@zinc powder with zinc powder includes the following steps: (1) Weigh 62.5g zinc powder, 140g dimethyl carbonate and 1.1g 2,6-di-tert-butyl-p-methylphenol, mix them evenly and add them to the reaction vessel. Start stirring and purge with nitrogen for 30 minutes. (2) Heat to 75°C; keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (3) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 130g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 62.7g of vinylene carbonate with a purity of 98.4% and a yield of 76%.

[0030] Comparative Example 2 The preparation method for vinylene carbonate by replacing activated carbon@zinc powder with zinc granules includes the following steps: (1) Weigh 62.5g of zinc granules (diameter ≥ 0.5cm), 140g of dimethyl carbonate, and 1.1g of 2,6-di-tert-butyl-p-methylphenol, mix them evenly, add them to the reaction vessel, start stirring, and purge with nitrogen for 30 minutes; (2) Heat to 75°C; keep stirring, weigh 150g of DCEC with a concentration of 37wt%, and add it to the reactor gradually over 30 minutes using a peristaltic pump. Then keep the temperature and react for 8 hours. Detect the reaction progress with gas chromatography. Stop the reaction when the DCEC content no longer decreases. (3) After the reaction is completed, the temperature is lowered to below 40°C, and zinc chloride and activated carbon particles are separated by filtration. They are washed with 30g of dimethyl carbonate and dried to obtain a mixed solid of about 130g of zinc chloride and activated carbon particles. The washing liquid and the filtrate are combined and desolventized under reduced pressure to obtain 16.3g of vinylene carbonate with a purity of 96.2% and a yield of 20%.

[0031] Experimental results show that this invention, using activated carbon@zinc powder as a dechlorinating agent, can improve the yield of vinylene carbonate. This indicates that the reactivity of activated carbon@zinc powder can be controlled within a suitable range compared to zinc powder and zinc granules, avoiding polymerization side reactions induced by rapid heating, while also improving reaction efficiency. Activated carbon@zinc powder can be recycled using byproducts from vinylene carbonate preparation, reducing production costs. This preparation method also effectively utilizes dichloroethylene carbonate, reducing environmental pollution.

[0032] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing vinylene carbonate by recycling ethylene dichlorocarbonate, characterized in that, Includes the following steps: (1) After the activated carbon@zinc powder is mixed evenly with the organic solvent and the polymerization inhibitor, it is added to the reaction vessel and stirred to carry out nitrogen replacement; the organic solvent is one or more of ethyl acetate, methyl tert-butyl ether, and dimethyl carbonate; (2) After heating to 60-80℃, add 37wt% dichloroethylene carbonate to the reaction vessel and keep the reaction at this temperature for 4-8 hours; (3) After the reaction is completed, solid-liquid separation is performed to obtain solid zinc chloride and activated carbon. The zinc chloride and activated carbon are washed, and the washing liquid and filtrate are combined and desolventized under reduced pressure to obtain vinylene carbonate.

2. The method according to claim 1, characterized in that, In step (1), the preparation process of activated carbon@zinc powder is as follows: zinc hydroxide precipitate generated by the reaction of zinc chloride solution with ammonia water is calcined and reduced by coke to generate gaseous zinc element. The gaseous zinc element is loaded into activated carbon particles by sublimation to obtain activated carbon@zinc powder.

3. The method according to claim 2, characterized in that, The mass ratio of activated carbon particles to gaseous zinc is 1:(2-4).

4. The method according to claim 2, characterized in that, The calcination temperature is 200–350°C, and the coke reduction temperature is 1000–1200°C.

5. The method according to claim 1, characterized in that, After washing the solid zinc chloride and activated carbon in step (3), they are dried, dissolved in water, filtered and separated to obtain activated carbon and zinc chloride solution. The zinc chloride solution is precipitated with ammonia, calcined and reduced with coke to obtain gaseous elemental zinc, which is then condensed and loaded onto activated carbon particles to obtain activated carbon@zinc powder.

6. The method according to claim 1, characterized in that, The mass ratio of the 37wt% dichloroethylene carbonate, activated carbon@zinc powder, organic solvent and polymerization inhibitor is (75-175):(60-200):(50-200):(1-2).

7. The method according to claim 1, characterized in that, In step (1), the organic solvent is dimethyl carbonate.

8. The method according to claim 1, characterized in that, In step (1), the polymerization inhibitor is one or more of 2,6-di-tert-butyl-p-methylphenol and 2,5-tert-di-tert-butylhydroquinone.

9. The method according to claim 1, characterized in that, In step (2), the 37wt% dichloroethylene carbonate is prepared by the following method: crude chloroethylene carbonate containing 82wt% chloroethylene carbonate, 7wt% dichloroethylene carbonate, 8wt% ethylene carbonate, water and other impurities is used as raw material. After separating the chloroethylene carbonate by vacuum distillation, it is then dehydrated by molecular sieve.

10. The method according to claim 9, characterized in that, The pressure of the vacuum distillation is -0.8 to -0.9 barG, and the temperature is 90 to 130°C.

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